Blow molded energy absorber and systems and methods of making and using the same

ABSTRACT

In one embodiment, a vehicle energy absorber system, comprises: blow molded crush lobes that are open on one side, wherein the energy absorber comprises fillets having a fillet radius of less than 20 mm and a thickness of less than or equal to 1.5 mm; a bumper beam adjacent the open side; and a fascia, wherein the energy absorber is located between the fascia and the bumper beam. In one embodiment, a method for making a blow molded energy absorber comprises: introducing a molten plastic to a first mold cavity; introducing gas into the plastic to conform the plastic to the interior of the first mold cavity and form a first preform; and separating the first preform along a centerline thereof to form open, first preform portions having first crush lobes.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 12/971,000, filed Dec. 17, 2010, the contents of which are herebyincorporated by reference.

BACKGROUND

The present disclosure relates generally to energy absorbers for use ina vehicle, for example, to reduce injuries (e.g., to occupant(s),pedestrian(s), etc.) and/or to reduce vehicle damage.

Increased importance has been placed on methods for minimizing theamount of injury suffered by a person in an accident as well as theamount of vehicle damage. Different regulatory committees assessautomotive pedestrian and occupant impact performance globally.Depending on the overall performance, vehicles are assigned a cumulativesafety rating. Each and every component of the vehicle needs to satisfythe specific impact criteria in order to ensure a good overall ratingfor the vehicle.

Foam energy absorbers are able to meet the pedestrian regulations, butrequire increased packaging space (e.g., greater than about 80millimeters (mm)). Metallic energy absorbers are too limiting in termsof the geometries and thicknesses that can be utilized and thus, are notvery efficient for pedestrian safety. Automobile manufactures arecontinually striving to reduce energy absorber component weight and/orreduce the packaging space of components to allow for increased stylingfreedom while simultaneously providing high performance energy absorbersystems. One approach is to lower the energy absorber component weightto provide a lower cost and lower weight solution. However, merelylowering the energy absorber component weight results in a compromise inperformance and styling freedom for the front end of the vehicle.Another approach has been to design an energy absorber with a lessexpensive material or various material configurations to provide a lessexpensive energy absorber. These material configurations are ofteninefficient at providing the desired structural integrity for energyabsorbers. Still another approach has been to modify the geometricalconfiguration of an existing energy absorber design. However, thisapproach has not resulted in a significant weight change. These existinglow performance systems generally require large amounts of packagingspace to meet the impact regulations. A large packaging space, however,reduces the vehicle styling freedom.

This generates the need to design an energy absorber that will deformand absorb impact energy to ensure a good vehicle safety rating with adecreased weight and lower amount of packaging space resulting in lowercost and increased design freedom. Different components due to theirinherent geometry and assembly requirements require different energyabsorber designs to satisfy the various impact criteria. Therefore, theautomotive industry is continually seeking economic solutions to improveoverall safety rating of a vehicle. Hence, there is a continual need toprovide a solution which would enhance a vehicle safety rating and/orreduce vehicle damage, while also providing design freedom.

BRIEF DESCRIPTION

Disclosed, in various embodiments, are energy absorbing devices that canbe used in conjunction with various vehicle components.

In one embodiment, a blow molded energy absorber comprises: a blowmolded first lobe section that has an open cavity on one side, and firstcrush lobes; and a blow molded second lobe section that has beenseparated into open, second preform portions that are located atopposite ends of the first lobe section, wherein the second lobe sectioncomprises second crush lobes. The first crush lobes and the second crushlobes are on a first side of the energy absorber.

In another embodiment, a blow molded energy absorber comprises: blowmolded crush lobes that are open on one side, wherein the energyabsorber comprises fillets having a fillet radius of less than 20 mm anda thickness of less than or equal to 1.5 mm.

In one embodiment, a vehicle energy absorber system comprises: a bumperbeam, a blow molded energy absorber, and a fascia. The energy absorbercomprises a blow molded first lobe section that has an open cavity onone side and first crush lobes, and a blow molded second lobe sectionthat has been separated into open second preform portions that arelocated at opposite ends of the first lobe section, wherein the secondlobe section comprises second crush lobes. The first crush lobes and thesecond crush lobes are on a first side of the energy absorber. Theenergy absorber is located between the fascia and the bumper beam, withthe open cavities on a side of the energy absorber adjacent the bumperbeam.

In another embodiment, a vehicle energy absorber system, comprises: blowmolded crush lobes that are open on one side, wherein the energyabsorber comprises fillets having a fillet radius of less than 20 mm anda thickness of less than or equal to 1.5 mm; a bumper beam adjacent theopen side; and a fascia, wherein the energy absorber is located betweenthe fascia and the bumper beam.

In one embodiment, a method for making a blow molded energy absorbercomprises: introducing a molten plastic to a first mold cavity;introducing gas into the plastic to conform the plastic to the interiorof the first mold cavity and form a first preform; and separating thefirst preform along a centerline thereof to form open, first preformportions having first crush lobes.

These and other non-limiting characteristics are more particularlydescribed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings wherein likeelements are numbered alike and which are presented for the purposes ofillustrating the exemplary embodiments disclosed herein and not for thepurposes of limiting the same.

FIGS. 1A and 1B show a front view of an embodiment of a blow moldedenergy absorber comprising inner lobes and outer lobe sections (FIG.1A); and an isometric view of an embodiment of a blow molded energyabsorber comprising inner lobes and outer lobe sections, disposedbetween a vehicle's beam and fascia (FIG. 1B).

FIG. 2 is isometric view of an embodiment of blow molded inner lobesprior to separation.

FIG. 3 is isometric view of an embodiment of blow molded outer lobesections prior to separation.

FIG. 4 is a cross-sectional schematic representation of blow moldedinner lobes taken along lines B-B of FIG. 2.

FIG. 5 is a cross-sectional schematic representation of blow moldedinner lobes taken along lines A-A of FIG. 2.

FIGS. 6-8 are side views of an embodiment of the method for producingthe blow molded energy absorber inner lobes.

FIGS. 9-11 are side views of an embodiment of the method for producingthe blow molded energy absorber outer lobe sections.

FIGS. 12-14 are a schematic side view of an embodiment of a method forproducing the blow molded energy absorber.

FIGS. 15-17 are a schematic side view of another embodiment of a methodfor producing the blow molded energy absorber.

FIG. 18 is a graphical representation of acceleration (G) versusintrusion (mm) for energy absorbers formed by thermoforming versusenergy absorbers having the same shape but formed by blow molding.

FIG. 19 is a graphical representation of force to the knee: acceleration(G) versus time.

FIG. 20 is a graphical representation of force to the knee: rotation(deg) versus time.

FIG. 21 is a graphical representation of force to the knee: shear (mm)versus time.

FIG. 22 is a graphical representation of force (kN) versus time (ms) fora pendulum impact.

FIG. 23 is a graphical representation of intrusion (mm) versus time (ms)for a pendulum impact.

DETAILED DESCRIPTION

Disclosed herein, in various embodiments, are energy absorberscomprising a plurality of lobes that are blow molded. The lobesgenerally comprise a thermoplastic material. The energy absorber, whenattached to a bumper beam, offers improved impact performance comparedto injection molded or thermoformed energy absorbers. The energyabsorber also offers a significant weight reduction (e.g., about 45% toabout 50% lighter) as compared to injection molded energy absorbers. Theenergy absorbers disclosed herein offer a more controlled thicknessdistribution and a reduction in the number of lobes or fillets spanningthe length of the energy absorber as compared to thermoformed energyabsorbers. Additionally, the energy absorbers comprising blow moldedlobes comprises a smaller corner fillet radius and thickness as comparedto thermoformed energy absorbers resulting in a more efficient energyabsorber (e.g., about 30% to about 40% more efficient). The energyabsorbers disclosed herein also reduce the damage incurred by a vehiclein a vehicle-to-vehicle impact such that the energy absorbers enable thevehicle to meet low speed vehicle damageability requirements. The energyabsorbers can utilize lower packing space (e.g., less than 45millimeters (mm)) while still meeting pedestrian safety impactrequirements (e.g., European Enhanced Vehicle-safety Committee (EEVC),European Automobile Manufacturers' Association (ACEA,) Phase II and, andGlobal Technical Regulations (GTR) along with the other low speed (e.g.,4 kilometers per hour (kmph)) FMVSS part 581, vehicle damageabilityrequirements (e.g., United Nations Economic Commission for Europe (e.g.,ECE-42) and Research Council for Automobile Repairs (RCAR), Allianz,Dunner (e.g., at 15 kmph, 10 degree inclined angled barrier hit tovehicle bumper at an outboard location), and Thatcham Impacts) onceassembled over the bumper beam. The design of the energy absorber inwhich sides of a lobe are molded together to form a closed structure andthen separated, partially or completely at the center facilitates easilyassembly of the energy absorber over the bumper beam.

Several categories of damages and injuries are possible when anautomobile accident occurs. One category relates to the safety ofpedestrians who may be injured during a vehicle to pedestrian impactevent. Another category relates to the damage of the vehicle componentswhen an impact with another vehicle or object occurs. Still anothercategory relates to the injury and safety of vehicle occupants during animpact with another vehicle or object. Injuries and vehicle damage inthe latter two categories are generally reduced with the use of a bumperbeam, crash cans, airbags, seatbelts, etc. Energy absorbers formulatedfor pedestrian protection are utilized to assist in reducing theinjuries suffered by a pedestrian upon an impact with a vehicle.Generally, energy absorbers are located in front of a bumper beam toprotect the pedestrian upon a collision with a vehicle.

Generally, energy absorbers can be processed and formed into the desiredshape by injection molding, thermoforming, or blow molding. Injectionmolding suffers from limitations on the minimum thickness that can beachieved, thus increasing the system mass. Thermoforming suffers frompoor control of thickness distribution and a requirement for a largefillet radius resulting in inefficient energy absorbing lobes. Energyabsorbers made by blow molding offer the ability to form lobes withthinner walls and smaller fillet radius resulting in a highly efficientenergy absorber. For example, the same lobe sizes made with differentfillet radius of 5 to 20 mm, were studied. Energy absorber lobes withsmaller fillet radius (5 mm) has shown better performance in absorbingenergy than the lobes with higher fillet radius (20 mm)). Note,generally for a thermoforming process, a minimum fillet radius of 20 mmwas required for the processability, whereas with the blow moldingprocess the energy absorber parts can be processed with smaller fillets,e.g., as small as 7 mm. Also, with blow molding, a thin wall can beattained, e.g., having a thickness of 0.7 mm while still meeting thedesired standards.

Exemplary characteristics of the energy absorbing assembly include hightoughness/ductility, thermal stability, high energy absorption capacity,a good modulus-to-elongation ratio, and recyclability, among others,wherein “high” and “good” are intended to mean that the characteristicat least meets vehicle safety regulations and requirements for the givencomponent/element. The energy absorber can comprise any thermoplasticmaterial or combination of thermoplastic materials that can be formedinto the desired shape and provide the desired properties, e.g., athermoplastic polyolefin (TPO). Exemplary materials includethermoplastic materials as well as combinations of thermoplasticmaterials with elastomeric materials, and/or thermoset materials.Possible thermoplastic materials include polybutylene terephthalate(PBT); acrylonitrile-butadiene-styrene (ABS); polycarbonate;polycarbonate/PBT blends; polycarbonate/ABS blends;copolycarbonate-polyesters; acrylic-styrene-acrylonitrile (ASA);acrylonitrile-(ethylene-polypropylene diamine modified)-styrene (AES);phenylene ether resins; blends of polyphenylene ether/polyamide;polyamides; phenylene sulfide resins; polyvinyl chloride PVC; highimpact polystyrene (HIPS); low/high density polyethylene (L/HDPE);polypropylene (PP); expanded polypropylene (EPP); polyethylene (PE); andthermoplastic olefins (TPO). For example, the bumper beam, energyabsorber, and/or crash can can comprise Xenoy®, which is commerciallyavailable from SABIC Innovative Plastics IP B.V. The bumper beam, energyabsorber, and/or crash cans can also be formed from combinationscomprising at least one of any of the above-described materials.

The overall size, e.g., the specific dimensions of the energy absorberwill depend upon its location in the vehicle and its function, as wellas the particular vehicle for which it is intended. For example, thelength (l), height (h), and width (w) of the energy absorbing assembly,will depend upon the amount of space available in the desired locationof use as well as the needed energy absorption. The depth and wallthickness of the energy absorber will also depend upon the availablespace, desired stiffness, and the materials (or combination ofmaterials) employed. For example, the wall thickness (t) of the energyabsorber can be less than or equal to 4.0 mm, specifically, 0.5 mm to1.5 mm, more specifically 0.5 mm to 1.0 mm, yet more specifically, 0.6mm to 0.9 mm, and still more specifically, 0.6 mm to 0.8 mm.

A more complete understanding of the components, processes, andapparatuses disclosed herein can be obtained by reference to theaccompanying drawings. These figures (also referred to herein as “FIG.”)are merely schematic representations based on convenience and the easeof demonstrating the present disclosure, and are, therefore, notintended to indicate relative size and dimensions of the devices orcomponents thereof and/or to define or limit the scope of the exemplaryembodiments. Although specific terms are used in the followingdescription for the sake of clarity, these terms are intended to referonly to the particular structure of the embodiments selected forillustration in the drawings, and are not intended to define or limitthe scope of the disclosure. In the drawings and the followingdescription below, it is to be understood that like numeric designationsrefer to components of like function.

FIG. 1 illustrates an energy absorber 10 comprising inner lobesection(s) 12 and outer lobe sections 14. FIG. 2 illustrates a view ofan inner lobe section 12 and an outer lobe section 14. As can be seenfrom FIG. 2, both inner lobe section 12 and outer lobe section 14comprise a closed structure that can be separated, partially orcompletely, into two halves to form the energy absorber 10. Alsoillustrated in FIG. 2, inner lobe section 12 and outer lobe section 14each comprise a plurality of lobes 16 on the surface of the inner lobesection 12 or outer lobe section 14. The lobes enable the energyabsorber to achieve high efficiency. For example, the energy absorberlobes can absorb lower leg impact energy about 500 Joules, in lesserpackaging space (e.g., less than or equal to 45 mm). The inner lobesection 12 and outer lobe section 14 also each comprise fillets 18comprising a radius (r). The radius of the fillets 18 can be less thanor equal to 20 mm, specifically, less than or equal to 15 mm, morespecifically 5 mm to 10 mm, and more specifically, 6 mm to 8 mm. Theradius of the fillets 18 on the blow molded energy absorber enables theenergy absorber thickness to be varied without increasing the overallweight of the energy absorber 10. For example, in one embodiment, thethickness of the lobes 16 can be different from that of the filletradius r.

Therefore, these blow molded energy absorbers can have a thickness downto 0.5 mm, while injection molded energy absorbers, for example, have athickness of greater than or equal to 1.8 mm due to processinglimitations. The substantially thinner walls help in significant weightreduction possibilities. Compared to thermoformed energy absorbers, blowmolding process offers greater design freedom (e.g., lesser filletradius and/or thickness control), and helps in improving theperformance.

The thickness of the lobe walls can be less than or equal to 4 mm,specifically, less than or equal to 1 mm, and even less than or equal to0.8 mm. In some embodiments, different portions of the lobe section hasdifferent thicknesses, with all of the thicknesses being less than orequal to 1.5 mm.

FIGS. 4 and 5 are cross-sectional illustrations of the inner lobesection taken along lines B-B and A-A, respectively of FIG. 2. FIGS. 5-8illustrate the process of preparing the inner lobe section forattachment to a vehicle. As can be seen, the inner lobe section can beblow molded as a two-sided, mirror image (FIG. 6), which is separated,e.g., cut (FIG. 7). The cut can be all the way through the center lineof the connected lobes, or can be sufficient to enable the lobes torotate 180 degrees around a common connection point. Optionally, theinner lobes can be joined at connecting point 22 between adjacent setsof inner lobe sections. Similarly, the mirror image blow molded outerlobes (FIG. 9) can be separated, rotated (FIG. 10), and moved to thedesired location with respect to the inner lobe sections (FIG. 11).

The inner and outer lobe sections can be attached to the vehicle viavarious methods such as mechanical attachments, e.g., screws, bolts,welding, snap features, clips, and so forth, as well as combinationscomprising at least one of the foregoing.

Other blow molded, open energy absorber designs are also contemplated.For example, the energy absorber can be “tuned” to meet a specific crushcharacteristic by adjusting the fillets, crowning, thickness, and/orcorrugations to absorb a desired amount of energy within the availablepackage space of a particular vehicle. Hence, the energy absorber cancomprise crowning, crush lobes separated by a base or wall, wherein thecrush lobes can comprise crowning, corrugations, and/or fillets.Furthermore, the wall thickness can be adjusted. In some embodiments,lobes in different areas can have a different thickness (e.g., the outerlobe section versus the inner lobe section).

The energy absorber can be formed in various manners that comprisetransforming a hollow, blow molded component comprising crush lobes intoan open, blow molded energy absorber. For example, the method of makingthe energy absorbers can comprise introducing molten plastic to a moldconfigured as two of the lobe sections, blowing a gas into the plasticto cause the plastic to conform to the shape of the mold with a hollowinner cavity, removing the formed plastic, cutting the lobe sections toform mirror image lobe sections, and rotating a lobe section so that alllobes on both lobe sections extend in the same direction. Depending uponthe particular design, one or multiple lobe sections are formed andarranged accordingly. For example, in FIGS. 6-11, separate inner andouter lobe sections are formed. The inner lobe section comprises twoportions that are arranged adjacent to one another, with the outer lobesections arranged on opposite ends of group of inner lobe sections. Thespecific number of inner lobe sections will depend upon the specificenergy absorber design.

FIGS. 12-14 illustrate an embodiment wherein the inner and outer moldportions are formed as a single element such that the hollow, blowmolded component (FIG. 12), is cut along the central axis, and the twopieces are unfolded (FIG. 13) to form the final energy absorber (FIG.14). As can be seen in this design, a single blow molded hollowcomponent is opened to form the final energy absorber. Here, the finalenergy absorber is a single unitary composition that was formed in situ.

FIGS. 15-17 illustrate an embodiment wherein a single, hollow, blowmolded element is opened (e.g., cut) along an axis to form the open blowmolded energy absorber. As can be seen, in this embodiment, two energyabsorbers can be formed from the single, hollow blow molded element.

Clearly, combinations of the above designs are also possible. Forexample, the inner lobe sections for two different energy absorbers canbe formed from a single, hollow, blow molded element similar to FIG. 16,wherein the outer lobe sections can be formed separately and added, suchas in FIGS. 9-11.

Once formed, the lobes can then be attached to a bumper beam or to asupport and then to a bumper beam. Possible attachments includemechanical attachments (e.g., clamps, screws, bolts, snaps, welds,and/or the like), and chemical attachments (e.g., bonding agents and soforth).

The energy absorbing assembly is further illustrated by the followingnon-limiting examples. All of the following examples were based uponsimulations unless specifically stated otherwise.

EXAMPLES Example 1 Weight and Acceleration

The complete energy absorber unit, assembled on a generic vehicleplatform, is simulated and validated for two major impacts (lower-legpedestrian impact and center pendulum impact as per United NationsEconomic Commission for Europe (ECE-42) protocols). The completeblow-molding energy absorber weighed approximately 300 grams (g),significantly lighter compared to the existing injection moldedthermoplastic solution (700 g) for the same packaging space. Asillustrated in FIG. 18, the blow molded design is observed to perform30% more efficiently than the thermoformed solution for a packagingspace of 42 mm. With the present design a maximum acceleration of lessthan 150 G can be attained, specifically less than 140 G, and even lessthan 130 G, while the thermoformed energy absorber had a maximumacceleration exceeding 165 G. The present results were attained at aweight of less than 500 g.

Example 2 Pedestrian Lower Leg Impact

Regarding lower leg impact, a generic vehicle platform with a 3 mm thickpolypropylene fascia, a glass filled lower spoiler, and a stiff memberon the top to emulate the hood are used in conjunction with the blowmolded energy absorber system. Here, the present blow molded energyabsorber is found to meet all the lower-leg impact targets as perEuropean Automobile Manufacturers' Association (ACEA,) Phase IIprotocols; namely acceleration of less than 150 G, rotation of less than15 deg, and shear of less than 6 mm. Actually, the present design canattain an acceleration of less than or equal to 140 G, specifically lessthan or equal to 130 G. The present design can attain a rotation of lessthan or equal to 12 deg, specifically less than or equal to 10 deg. Forshear, the present design can attain a result of less than or equal to 5mm, specifically less than or equal to 4.5 mm. (See FIGS. 19-21)

Example 3 Center Pendulum Impact

The present energy absorber system is also found to perform well forcenter pendulum impact (e.g., impact on the inner lobe sections),including meeting ECE-42 regulatory requirements. FIGS. 22 and 23 showthe performance numbers for this impact case as force in kiloNewtons(kN) versus time in milliseconds (ms), and as intrusion in millimeters(mm) versus time (ms), respectively. As can be seen, for the period of60 milliseconds, the force levels are maintained less than 15 kN and theintrusion levels are maintained at less than or equal to 64 mm.Actually, the force levels were maintained at less than or equal to 12kN, and even less than or equal to 10 kN for the period of 60 ms.

The present design is a lightweight, highly efficient, blow-molded,pedestrian-safe, energy absorbing system for automobiles. The energyabsorbing lobes for the entire energy absorber can be formed as a set oftwo which are separated to form the inner and outer lobe sections. Dueto a lower thickness (e.g., less than 1.5 mm) a lighter weight energyabsorber can be formed (e.g., less than 500 g), compared to thermoformedenergy absorbers that have a thickness of greater than or equal to 2 mmdue to process limitations that prevent the formation of thinner walls.Thermoformed energy absorbers have a weight of greater than 500 g andeven greater than or equal to 700 g. However, the present blow moldedenergy absorber with a lighter weight and thinner wall, has better lowerleg impact characteristics than the thermoformed energy absorber.

The present design and method forms open, blow molded energy absorberlobes that have a reduced thickness and/or fillet radius as compared toenergy absorbers formed by other processes such as thermoforming andinjection molding. As is understood, during blow molding, the formedcomponent is a closed, hollow component. In the present design, thatclosed, hollow component is separated to form open components (e.g.,components that have a cavity on one side; i.e., the side that wasoriginally part of the inside of the hollow cavity). The open cavity canbe located adjacent to a bumper beam or other support structure thatwill provide sufficient structural integrity to enable the crush lobesto crush in a desired manner during an impact.

In one embodiment, a blow molded energy absorber comprises: a blowmolded first lobe section that has an open cavity on one side and firstcrush lobes; and a blow molded second lobe section that has beenseparated into open second preform portions that are located at oppositeends of the first lobe section; wherein the second lobe sectioncomprises second crush lobes. The first crush lobes and the second crushlobes are on a first side of the energy absorber.

In another embodiment, a blow molded energy absorber comprises: blowmolded crush lobes that are open on one side, wherein the energyabsorber comprises fillets having a fillet radius of less than 20 mm anda thickness of less than or equal to 1.5 mm.

In one embodiment, a vehicle energy absorber system comprises: a bumperbeam, a blow molded energy absorber, and a fascia. The energy absorbercomprises a blow molded first lobe section that has an open cavity onone side, and first crush lobes; and a blow molded second lobe sectionthat has been separated into open, second preform portions that arelocated at opposite ends of the first lobe section, wherein the secondlobe section comprises second crush lobes. The first crush lobes and thesecond crush lobes are on a first side of the energy absorber. Theenergy absorber is located between the fascia and the bumper beam, withthe open cavities on a side of the energy absorber adjacent the bumperbeam.

In another embodiment, a vehicle energy absorber system, comprises: blowmolded crush lobes that are open on one side, wherein the energyabsorber comprises fillets having a fillet radius of less than 20 mm anda thickness of less than or equal to 1.5 mm; a bumper beam adjacent theopen side; and a fascia, wherein the energy absorber is located betweenthe fascia and the bumper beam.

In one embodiment, a method for making a blow molded energy absorbercomprises: introducing a molten plastic to a first mold cavity;introducing gas into the plastic to conform the plastic to the interiorof the first mold cavity and form a first preform; and separating thefirst preform along a centerline thereof to form open, first preformportions having first crush lobes.

In the various embodiments, (i) the first lobe section can be a singleportion located between the second preform portions; and/or (ii) thefirst lobe section and/or the second lobe section can have a thicknessof 0.5 mm to 1.5 mm; and/or (iii) the thickness can be 0.6 mm to 0.9 mm;and/or (iv) the first lobe section and/or the second lobe section canhave fillets with a fillet radius of less than or equal to 15 mm; and/or(v) the fillet radius can be 5 mm to 10 mm; and/or (vi) the filletradius can be 6 mm to 8 mm; and/or (vii) the first lobe section cancomprise greater than or equal to two first preform portions having thesame design.

In various embodiments, the method can comprise: (i) orienting the firstpreform portions adjacent to each other so that all of the first crushlobes are oriented in the same direction; and/or (ii) introducing amolten plastic to a second mold cavity; introducing gas into the plasticto conform the plastic to the interior of the second mold cavity andform a second preform; separating the second preform along a centerlinethereof to form open, second lobe sections having second crush lobes;and locating one of the second lobe sections on opposite ends of aninner lobe portion comprising the first lobe section; wherein all of thecrush lobes are oriented in the same direction; and/or (iii) attachingthe first preform portion to a bumper beam.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other (e.g., ranges of“up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, isinclusive of the endpoints and all intermediate values of the ranges of“5 wt. % to 25 wt. %,” etc.). “Combination” is inclusive of blends,mixtures, alloys, reaction products, and the like. Furthermore, theterms “first,” “second,” and the like, herein do not denote any order,quantity, or importance, but rather are used to d one element fromanother. The terms “a” and “an” and “the” herein do not denote alimitation of quantity, and are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The suffix “(s)” as used herein is intended toinclude both the singular and the plural of the term that it modifies,thereby including one or more of that term (e.g., the film(s) includesone or more films). Reference throughout the specification to “oneembodiment”, “another embodiment”, “an embodiment”, and so forth, meansthat a particular element (e.g., feature, structure, and/orcharacteristic) described in connection with the embodiment is includedin at least one embodiment described herein, and may or may not bepresent in other embodiments. In addition, it is to be understood thatthe described elements may be combined in any suitable manner in thevarious embodiments.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or may be presently unforeseen may arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they may be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

What is claimed:
 1. A method for making a blow molded energy absorber,comprising: introducing a molten plastic to a first mold cavity;introducing gas into the plastic to conform the plastic to the interiorof the first mold cavity and form a first preform; separating the firstpreform along a centerline thereof to form open, first preform portionshaving first crush lobes; and orienting the first preform portions sideby side so that all of the first crush lobes are oriented in the samedirection.
 2. The method of claim 1, further comprising attaching thefirst preform portion to a bumper beam.
 3. The method of claim 1,wherein the energy absorber weighs less than 500 g, and wherein, whenusing a packaging space of less than 45 mm, and once assembled with abumper beam, provides acceleration of less than 150 G, rotation of lessthan 15 degrees and shear of less than 6 mm in a pedestrian leg impacttest.
 4. The method of claim 1, wherein the energy absorber is capableof absorbing lower leg impact energy of about 500 Joules in a packagingspace equal to or less than 45 mm.
 5. A method for making a blow moldedenergy absorber, comprising: introducing a molten plastic to a firstmold cavity; introducing gas into the plastic to conform the plastic tothe interior of the first mold cavity and form a first preform;separating the first preform along a centerline thereof to form open,first preform portions having first crush lobes; introducing a moltenplastic to a second mold cavity; introducing gas into the plastic toconform the plastic to the interior of the second mold cavity and form asecond preform; separating the second preform along a centerline thereofto form open, second lobe sections having second crush lobes; andlocating one of the second lobe sections on opposite ends of an innerlobe portion comprising the first lobe section; wherein all of the crushlobes are oriented in the same direction.
 6. The method of claim 5,further comprising attaching the first preform portion to a bumper beam.7. The method of claim 5, wherein the energy absorber weighs less than500 g, and wherein, when using a packaging space of less than 45 mm, andonce assembled with a bumper beam, provides acceleration of less than150 G, rotation of less than 15 degrees and shear of less than 6 mm in apedestrian leg impact test.
 8. The method of claim 5, wherein the energyabsorber is capable of absorbing lower leg impact energy of about 500Joules in a packaging space equal to or less than 45 mm.